Ancient 'Ghostbuster Demon' Creatures Pooped Together

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Enormous herds of rhinolike animals turned parts of what is now
Argentina into minefields of dung, new fossils reveal.

These massive herbivores were dicynodonts, mammal-like reptiles
that looked something like a cross between a rhinoceros and the
demon dogs from "Ghostbusters." Argentine researchers have now
found that these dicynodonts pooped in communal latrines,
designated areas for depositing dung.

Many modern-day animals, including elephants, llamas and rhinos,
poop in communal latrines. Even
raccoons do it, much to the irritation of homeowners whose
backyards are chosen as the places to defecate. Fossilized hyena
poop from several hundred thousand years ago was deposited in
communal latrines, but the behavior has not been found further
back in the fossil record.

"This is the only case of megaherbavore latrine and it's the
oldest," found fossilized, said study researcher Lucas Fiorelli
of the Centro Regional de Investigaciones Científicas y
Transferencia Tecnológica in La Rioja, Argentina.

Herd of reptiles

Fiorelli and his colleagues began excavating in northwest
Argentina two years ago and quickly uncovered fossilized poop
— known as
coprolites — by the bucket load. These coprolites date back
to the middle Triassic, 240 million years ago. In this era, small
dinosaurs were just beginning to appear, but the world belonged
to strange mammal-like reptiles, including the famous sail-backed
Dimetrodon . [ Gallery:
The Diversity of Dinosaur Ancestors ]

In some areas, there were as many as 94 rounded fossil poops
every 10 square feet (1 square meter). The coprolites varied in
size from just about half an inch (1 centimeter) in diameter to
more than a foot (35 cm) wide. Such variation in such a small
area strongly suggested a herd of young and old animals living
together, defecating communally.

In total, the researchers found eight separate latrine spots.
Most of the coprolites were oval or spherical, with a few
"sausagelike" outliers and a few shaped like cow patties. The
only animal large enough to produce dung balls more than a foot
in diameter in this region was Dinodontosaurus, a beaky,
tusked bruiser that could weigh up to 6,600 pounds (3,000
kilograms). In comparison, a modern African female bush elephant
weighs about 8,000 lbs. (3,600 kg).

Communal pooping

Modern animals use communal latrines for communication — a big
pile of dung can say anything from "dominant male lives here" to
"fertile female nearby!" Communal defecation also prevents
animals from spreading parasites, because they don't poop where
they eat, Fiorelli said. It's not possible to know why
Dinodontosaurus engaged in communal pooping, but the
behavior could have served a similar purpose.

"It's an important social behavior," Fiorelli said. "They were
gregarious animals."

The discovery is not only the first evidence of Triassic communal
latrines; it's also the first direct evidence of
Dinodontosaurus's diet. Most researchers agreed that
this weird creature was a vegetarian, but only based on the
animal's beaklike jaw. The gray-brown coprolites contained no
animal bones, only woody plant material, seeds and pollen,
Fiorelli and his colleagues found. The analysis reveals that
Dinodontosaurus was indeed herbivorous.

Fiorelli and his colleagues have plans for more excavations in
the region. They also plan to take a closer look at the
Dinodontosaurus poop, which provides direct evidence of
the kind of plants that were in the area 240 million years ago.

"In the formation, you have no record of plants, only animals,"
Fiorelli said. "Now, with the coprolite, you can know about the
paleobotany of the formation."